Spark plasma sintering of TiN-cubic BN composites

TiN-cubic boron nitride (cBN) composites were prepared from TiN and cBN powders by spark plasma sintering at temperatures from 1600 to 1800°C for 600 s under a uniaxial pressure of 100 MPa. The densification, phase transformation, microstructure and mechanical properties of the TiN-cBN composites were investigated. TiN-BN composites originally containing 10 to 30 vol% cBN without a phase transformation from cBN to hexagonal BN (hBN) were obtained at a sintering temperature of 1600°C. The densification of the TiN-BN composites was retarded with increasing cBN content. The phase transformation from cBN to hBN in the TiN-BN composites started at 1650°C and was completed at 1800°C. The Vickers hardness and fracture toughness of TiN-BN composite, originally containing 10 vol% cBN, prepared at 1600°C were 17 GPa and 3.6 MPa·m1/2, respectively.